Several FertilityCare Centers and the University of Utah are conducting a study to evaluate the effectiveness of the Creighton Model (CrM) for new and return users wanting to avoid pregnancy. While past studies have shown that the Creighton Model is a highly effective method, this study will use new ways to measure how well it works. This is important because the knowledge gained will improve comparisons between the Creighton Model and other family planning methods. The study will also explore intentions and behaviors of couples to avoid or achieve a pregnancy.